Hydraulic pumping system and by-pass valve therefor



Dec. 29, 1953 HYDRAULIC PUMPING SYSTEM AND BY-PASS VALVE THEREFOR Filed March 19, 1948 c. J. COBERLY 2,664,102

3 Sheets-Sheet 1 llyvli/vTok. CLARENCE d. COBERLY BY HIS ATTORNEYS- HA RR/S, K/ECH, Fos TER & HARRIS \6) x Dec. 29, 1953 c. J. COBERLY 2,664,102

HYDRAULIC PUMPING SYSTEM AND BY-PASS VALVE THEREFOR Filed March 19, 1948 3 Sheets-Sheet 2 F .14; 85 Fig.5. 64

/'N VENTO/P. CLARENCE'J. Case/aw BY HIS ATTORNE Y5.

HARRIS, K/ccH, F05 TER &HA RR/s 0v Dec. 29, 1953 COBERLY 2,664,102

HYDRAULIC PUMPING SYSTEM AND BY-PASS VALVE THEREFOR Filed March 19, 1948 3 Sheets-Sheet 3 CLARE NCDJCOBERLY BY HIS ATTORNIYS.

Patented Dec. 29, 1953 HYDRAULIC PUMPING SYSTEM AND BY-PASS VALVE THEREFOR Clarence J. Coberly, Los Angeles, Calif., assignor, by mesne assignments, to Dresser Equipment Company, Cleveland, Ohio, a corporation of.

Ohio

Application March 19, 1948, Serial No, 15,848 10 Claims. (Cl. 137-490) This invention relates to valves for the relief ofpressure and'more particularly to valves for by-passing fluid in systems of hydraulic pumping wherei'n a large quantity of high pressure ope'rating fluid must be handled at an accurately controlled pressure.

The invention is of particular utility in the oil industry, and is described in connection with such use, although its utility is not limited to that field.

In the operation of fluid-operatedpumps in oil wells, fluid is pumped at high pressure to the pumps located within the wells, and this operatihg fluid, which enters the pumps and causes movement of their mechanism, is usually crude cil which has been filtered and cleaned of foreign materials. The wells are frequently of great depth and the pressure in the supply lines extending down the wells to the pumps is the pressure of the hydrostatic head in the tubing multiplied by the area ratio of the engine topump piston in the bottom hole unit. The individual supply lines and pumps are therefore usually provided with protective devices by which the pressure applicable to them may be limited.

It is common practicev in the oil industry to operate a number of fluid-operated well pumps from a central pumping station, the pumping station including one or more conventional triplex surface. pumps connected so as to supply power oil through a supply manifold and piping to all of the well pumps in the system. In, such a system, the well pumps are normally operated at dififereht depths and at different rates, the speed of operation of each well pump being controlled and governed by a flow governor, such as. shown in my Patent No. 2,119,737, for example, which is commonly installed in the power oil tubing leading to each of the well pumps. The maximum fluid pressure developed in the supply manifold by the central pumping station as a prac tical matter must be maintained at a value at least slightly greater than that required for the well pump in the system having the greatest pumping head and requiring power oil of the highest pressure. In addition, the total volume of power oil delivered by the central pumping station to the supply manifold must be slightly greater than enough to operate all of the well pumps in the system when they are operating at their maximum production capacities, so as to prcvide a slight excess of pressure to the sup ply manifold Conseo uently, there is also an excess volume of'power oil deliveredhy the central pumping station .to the supply manifold, and

this excess fluid must be continuously by-passed from the supply manifold to the low pressure reservoir from which the triplex pumps draw their,

supply. Also, in the operation of such a system,

, frequently the operation of one ormore ofithe well pumps is stopped for repairs or for other purposes which, of course, increases substantially the amount of power oil that must be bypassed from the supply manifold to the reservoir. If all power oil remaining. in the system.

The triplex surface pumps in such a system are usually provided with conventional pressure relief valves of the spring-held poppet type, but such valves are not intended for use as by-pass valves, and are usually incapable of lay-passing a wide range of capacities without wide. pressure fluctuations in the manifold pressure. At the normally high fluid pressures involved in such a system, normally in excess of 2000 pounds per square inch, conventional pressure relief valves are wholly inadequate.

It is therefore a primary object of my invention to provide a pressure controlled by-pass valve for a hydraulic pumping system having incorporated therewith means for overcoming. the above discussed undesirable conditions and difi'lculties.

It is a further. object of my invention to provide a pressure by-pass valve that will discharge a large volume of fluid at a pressure closely llm ited to a predetermined value.

Another object of. my invention is to provide a pressure controlled by-pass valve which will maintain pre sure at a definite value while discharging a widely variable volume of fluid.

A further object of my invention is to provide a pressure controlled by-pass valve operable without chattering at a pressure so closely limited as to be substantially constant, and capable oi discharging a large volume of fluid.

Yet another object of my invention is to pro vide a pressure by pas's'valve adapted to discharge into' a'clos'ed system but so constructed that the effect of back pressure in the closed sys tem upon the operation of the valve is minimized and the pressure at which the valve operates is not materially varied thereby.

A still further object of my invention is to provide a pressure controlled by-pass valve in which a main valve is operated in response to an actuating valve assemblage discharging into the same system as the main valve, which systern may be closed and under pressure.

Another object of the invention is to provide a by-pass valve which may be used in connection with a manifold flow control valve, such as shown in my copending application Serial Number 748,921, filed May 19, 1947, to form units of a manifold assembly.

Other objects and advantages will appear in the following specification and in the drawings, in which:

Fig. 1 is a utility view, diagrammatically showing a fluid-operated pumping system embodying my invention;

Fig. 2 is a simplified diagrammatic view illustrating the principal parts and passages of my invention;

Fig. 3 is a plan view of my invention shown as installed upon a section of a manifold;

Fig. 4 is an elevational view taken from the right of Fig. 3;

Fi 5 is a vertical sectional view, on an enlarged scale, taken on the line 55 of Fig. 3; and

Fig. 6 i horizontal sectional view, taken on the line 6-6 of Fig. 5.

Referring to Fig. l, I show a settling tank I having a discharge pipe 1a, a production pipe 8 adapted to convey well production from a pluralit of wells 9 and 9a, and a supply pipe II]. The supply pipe i connects with a triplex surface pump H adapted to draw well fluid from the settling tank I, which acts as a reservoir, and is adapted to supply it as power oil under relatively high pressure to a supply manifold l2 and thence through suitable supply tubings l3 and 3a to each of the wells 9 and 9a, respectively, through metering valves l4 and Ma, respectively. The metering valves I4 and 4a are preferably of the type shown and described in my copending application Serial Number 748,921, filed May 19, 1947, and are each adapted to supply power oil at a selected volume and pressure to their respective wells, which volumes and pressure are normally different. Although I have shown only the two wells 9 and 9a, it is to be understood that normally a large number of such wells may be supplied with power oil from the triplex pump II, or a number of such pumps. It is also to be understood that although only one triplex pump H is shown, for simplicity, a multiple well installation will normally utilize a number of such pumps operating to deliver power oil from the settling tank I to the supply manifold I2, and such triplex pumps, whether one or a number, may be installed at a central pumping station which may be remote from the wells supplied thereby,

Also connected to the supply manifold I2 is a by-pass valve l5, which constitutes a principal element of the present invention. the same being adapted to provide fluid communication between the supply manifold l2 and the production pipe 8 through a discharge pipe Ia, as will be described in detail hereinafter.

The well 9 is a conventional installation, including a perforated casing l6 having a. production tubing I! set therei and a fluid-operated well pump [8 set in the production tubing. The well pump I8 is supplied with power oil to actuate it through power oil tubing I!) which connects with the supply tubing l3. As will be understood, the production pipe 8, or a branch thereof, connects with the production tubing I1 and is adapted to convey the well production from the fiuidoperated well pump l8 to the settling tank I. The well 9a is provided with a similar bottomhole installation (not shown), and is similarly connected to the supply tubing 13a and the production pipe 8. As will also be understood by those skilled in the art, the well pumps, such as I 8, may and probably will, be set at different levels in their respective wells, pump against different heads, and otherwise operate under different bottom-hole conditions, requiring different volumes of power oil to be delivered thereto at dilferent pressures.

As best shown in Figs. 3-6, the by-pass valve [5 includes a manifold section, comprising a. part of the supply manifold I 2, to which a housing 2| is secured by bolts 22. The manifold section 28 forms part of the supply manifold [2, the metering valves I4 and Ma being provided with identical manifold sections, all of which are adapted to be bolted together in longitudinal alignment with a suitable cap a closing the end section. As will be apparent, such a manifold construction permits any desired number of metering valves, such as the valves [4 and Ma, to be readily connected or disconnected from the pumping system, which readily permits the addition of additional well pumps to the system, or the withdrawal thereof from the system, and this is a. further valuable feature of the invention.

The manifold section 20 is provided with a manually-operated valve 23, which is mounted on a valve stem 24, protected and secured by a locking cap 25, and which seats upon a valve seat 26 threadedly secured in a port 21 aligned with an inlet port 28 in the housing 2|. The manifold section 20 and the housing 2| are sealed to each other by an annular ridge 29 on the manifold section which fits within an annular groove 30 in the housing and is there held against a gasket 3|. The discharge pipe |5a is secured to a flange member 33, which is secured to the housing 2| in alignment with a discharge port 34 by studs 35, and is sealed to the housing in the same manner as the manifold section 20 by an annular ridge 36 held against a. gasket 31 in an annular groove 38.

The housing 2| is provided with a cylindrical chamber 40 in axial alignment with the inlet port 28 and connected thereto by a coaxial bore 4| and a second coaxial bore 42 of less diameter than the bore 4|. A valve casing 43, comprising an upper casing member 44 and lower casing member 45 threaded thereto, is threadedly secured in the chamber 40, the upper casing member 44 having a flange 46 limiting the entry of the valve casing 43 into the chamber 40 so as to cause registering of connecting passages hereinafter described. The lower casing member 45 has an extension 41 fitting closely within the bore 4| and extending partly therethrough, and a further extension 48 fitting closely within the bore 42. The reduced diameter of the extension 48 leaves an annular space 49 around that part of the extension 48 contained in the bore 4 I.

A main valve 58 and a valve pilot 5| are housed within the valve casing 43, with the main valve 50 in communication with the inlet port 28 by means of an axial passage 52 in the lower end of the extension 48 and in communication with the annular space 49 by means of radial ports 53 in the extension 48. A valve seat 54 is provided for 'ing'screw 65 and the nozzle-54.

themain valve50 atthe upper'end ofthe-axial I5 when the main valve 50 is open. Plugs 58 close the outer ends of the passages 51.

A master control valve '60 is mounted infa v chamber 6I formed in the housing 2| between the main flow passages 51. The mastercontrol-valve 50 has a valve body'52 threadedly secured within the chamber GI and sealed therein by a sealing ring '63, and a nozzle 84 threadedly secured in the lower end of the'valve body 62. "An adjusting screw 65 is movably threaded inthevalve body 62 to regulate a spring loaded pressure'-re lease mechanismmounte'd between the adjusthas a coaxial bore66 at its lower end, communicating through a horizontal passage '61 with an inclined passage 58 which leads from'the inlet port 28 on the upstream-side of themain valve 59. The horizontal passage 61 is closed at its :5

outer end by a plug 69. -A chamfered boss'lO on the lower face of the nozzle 54 is threaded'into the lower end of the valve-body'fi so as to leave a space H therebelow in the lower portion of the chamber 6 I. 62 is proportioned to leavean annular space I2 between'the valve body'62 and the wall ofthe chamber 6| 'Circumferentially disposed longitudinal passages "I3 through the nozzle 164 lead from the interior 'o'f'the valve body 62 tothespa'ce I! and thence to the annular space I2.

An axial passage '75 extends through" the nozzle 64 and through "an axialupward extension I8 which is chambered'to terminate in a knife edge valve seat 'Il annularly surrounding the axial y passage I5. An optically fiat valve head =18, of hard metal or sapphire, is held by a yoke 19 which has a sliding fit on the axial extension IE. The valve head 18 is pressed against the valve seat '11 'by a spring '8; bearing against the yoke 19 and reacting against a spring follower 8! which-is engaged by the adjustingscrewliE and'so positioned as to give the spring 80 any "desired initial loading. To allow the 'valvehead I8 to rotate and thereby to wear evenly on the valve seat "II,

the adjusting screw 65 has a conical point 82 engaged by a more obtuse conical recess 83 in the spring follower BI. A micrometer thimble 84 is secured to the upper end of the adjusting screw 35 by aset screw-85, to'register with a calibrated skirt 8%. The thimble 8'4 and skirt fifiimaybe calibrated in pounds per square inch or other convenient units indicative of the pressure against the valve head I8. To "permit-adjusting the spring 86 to an exact spring rate'to which the thirnble 84 and skirt 8% maybe calibrated, the spring is threaded upon a round bottom helix--87 formed on the outside of the spring follower 8|, and is soldered thereto when'correctly adjusted.

Packing '58, compressed by a packing nut 189,15

The chamber 6| Y.

The lower portion of thevalve' body I v flve' seat the valve head 1-8 to the in- -'downwardly-extending central boss 58 perforated with an' aXiaIbore-SIII which forms a guide or bushing for the stem 100 df the "pilot valve 5|. "The stem "lw has-alower contracted portion I!) I -terminatin'g in anee'dle IM, and anupp'er contracted portion 103 tightly pressed "into a pilot 'val-Ve pi-stQn I04, whichisrecipr'ocable in theup "per cyIincIerl 'QG. A spring I'05,-guided'in a recess I flfi in the upper casing member 44 and bya boss Illl 'on the 'piIotWaIVe piston 1 I04 urges the piston I04 a'ncl "the attach'e'd needle "I 02 downwardly.

-A*'mai-n valve "piston I-O'B is reciprocably mount- "ed in the lower cylinder -97, with'a 'sliding fit on both the lining s'leeve m andithe pilot valve stem 7 I DDQ-and 'h'as a downwardly-extending tubular piston rod I69 -terminating in a'main valve head I I designed to seat" in" the valve seat 54. Springs I I I and II2,'reactingagainst-the partition 93 and "guided by shoulders H13 on theflatt'er and I I 4 on the piston 1I II8,:ur'ge the pist'on downwardly to normally maintain the main 'valve 50 closed. 'Ihe' lower portion of 'zth'e tubular piston rod I 29 isIcontracted in ertternal diameter to provide an l'annular-space II Ii5-within the extension -41 of the lowerzcasingsmeniber45 whichis a1ways in registr-y with theiraclialp'orts 53 at any position with- ;in?tlre scope :or "movement f the tubular piston ro'd m9. Themain valvevhead I III is perforated "with-apassage't-I 6:into which:the needle I02 seats i to 5 form aa iclosure.

When the needle I02 is lifted from the massage -'I='I6, rfluid may fiow from the inlet port=28 through that-passage -I I6 to an annular space II:'I between the lower contracted portion #IIII of the pilot valve stem H and the wall of the tubular Ep'iston rod I09. A radial port I'Iefl in the tubular piston rod I09 per- =mits this fluidto'enter ai space I I9 below themain valve piston vHIB where thefluidpressure tends to compress the springs III and -I I2 and to open themain-valvesw. A helical groove I2IJ on the cuter:surface of-the tubularpiston rod I05 then permits the fluid to flow to the annular space 2 I5 and thence-throughfthe'radial ports 53 and the main fiDWFIJASSflgBS '51 :to the discharge port 3i, but forms a resistance-v-which preserve the fluid pressure inthespace H9 at a-higher level than the lpressureirntl'ie main flow passages 51.

When the control valve opens, as will be 'describedhereinafter power oil under high pressure may flow ffrom the inletport 23 through the inclined passage -68 rand the horizontal passage eL-theconical bore afi-firtheaxial passage I5, the "radial ports 80, theg passages l3,space H, and .annular space 12 .into jthe inclined passage 9! from which the fluidlpasses to anannular groove I21, ion the outer surface of the upper casing member 44, and :thence through :a passage I22 in the upper ceasing .:member 44 to aspace I23 between the partition '93 "and the pilot valve .pis-

ton I04, where the pressure of the fluid tends to move the pilot valve piston upwardly and, consequently, to open the pilot valve 5|. The upper casing member 44 is sealed to the wall of the chamber 40 above and below the annular groove |2| by sealing rings I24, to prevent loss of pressure. A helical groove I25 on the outer surface of the pilot valve stem I permits the fluid to flow from the space I23 to radial ports I25 in the pilot valve stem I00, the groove being of small cross-sectional area so as to resist loss of pressure from the space I23. The helical groove I25 communicates with the upper side of the main valve piston I08, entering the lower cylinder 91 between the main valve piston I08 and the central boss 98 on the partition 93. The radial ports I25 communicate with the upper side of the pilot valve piston I04, through an axial passage I21 in the pilot valve stem I00. The pressure residual in the fluid after passing through the helical groove I25 is therefore available to supplement the spring I in tending to close the pilot valve 5|, and to supplement the springs I I I and H2 in tending to close the main valve 50. Fluid entering the upper cylinder 96 above the pilot valve piston I04 is returned to the radial ports I26 through the axial passage I21 when the piston rises, and so enters the lower cylinder 01. Fluid entering the lower cylinder 91 on the upper side of the main valve piston I08 escapes therefrom by a longitudinal escape vent I28, provided in the external surface of the tubular piston rod I09 and which communicates with the annular space 5 and thence through the main flow passages 51 to the discharge port 34. The escape vent I28 is of such cross-sectional area that it does not act as a restriction to the flow of the fluid therethrough, but permits the fluid pressure on the upper, or low-pressure, sides of the pistons I04 and I08 to be approximately the same as the pressure in the production pipe 8, thereby obtaining higher pressure differentials across the pistons I04 and I08 when fluid is admitted to the lower, or high-pressure, sides of those members so as to more effectively move them.

As best shown in Fig. 6, to allow for drainage when it is desired to remove the valve casing 43 or other operating parts, a drainage bore I30 is provided in the housing 2|, and is fitted with a drain pipe I3I secured to its outer end by any suitable fittings and leading to any convenient pit or receptacle. A valve I32, seated in a bore I33 of stepped diameter in continuation of one of the main flow passages 51, opens and closes communication between that main flow passage and the drainage bore I30 through a connecting passage I34.

In the operation of the by-pass valve I5 with particular reference to Figs. 1 and 2, it may be cut in or out of the supply manifold I2 of which the manifold section 20 is a part by manually opening or closing the manual valve 23, respectively.

When the manual valve 23 is opened power oil under high pressure flows from the supply manifold I2 and the manifold section 20 into the inlet port 28 of the housing 2|. The main valve springs III and H2 are selected so as to exert a closing force on the main valve piston I08 and, consequently, on the main valve 50 equal to the maximum fluid pressure desired or to be .allowed in the supply manifold I2. Thus, for example, if the maximum fluid pressure desired or allowable in the supply manifold I2 is 5000 pounds per square inch, the springs III and H2 are selected so as to maintain the main valve 50 closed until the fluid pressure in the inlet port 28 exceeds this value. When the fluid pressure in the inlet port 28 exceeds such value for which the main valve springs III and H2 are selected, they are overbalanced by such excessive fluid pressure and the main valve pops open, permitting power oil to flow from the supply manifold I2 past the main valve 50, through the radial ports 53 and the annular space 49 into the main flow passages 51, from which such fluid flows into the discharge pipe I5a and thence through the production pipe 8 into the settling tank 1. It will therefore be appreciated that the main valve 50 acts as a pressure relief valve to limit the fluid pressure in the manifold section 20, and, consequently, in the supply tubing I3 and I3a, to a value below a predetermined maximum. This pressure-relief action of the by-pass valve I5 is an important feature of the invention, but is secondary to the by-pass function of the valve which will now be described.

When the manual valve 23 is opened, power oil under high pressure also flows through the inclined passage 68, the horizontal passage 61, the coaxial bore 66, and into the axial passage 15, to exert an upward force on the bottom of the valve head 18 tending to move the valve head up off its seat 11 to open it, against the action of the spring 80. The downward force exerted by the spring on the valve head 18 tending to maintain the valve head closed may be varied as desired by rotating the thimble 84, to increase or decrease the compression on the spring 80. The compression of the spring 80 may thus be varied from zero to As will be understood, however, if the compression of the spring 80 is increased to a value such that the closing force exerted by it on the head 18 more than balances the fluid pressure on the upstream side of the main valve 50 for which the main valve springs III and H2 have been selected, the main valve 50 will simply open to relieve excess pressure, However, if the compression of the spring 80 is adjusted to a value overbalanced by the fluid pressure in the inlet port 28 and axial passage 15, but lower than the fluid pressure for which the main valve springs III and H2 have been selected, e. g., lower than 5000 pounds per square inch, then such fluid pressure will move the valve head 18 upwardly, pe mitting fluid to flow therepast, through the radial ports 00, the interior of the valve body 62, the passages 13, the space 1| and into the annular space 12 around the lower end of the valve body 02. From there, such fluid flows throu h the inclined passage 9|, the annular groove I2I, and the passage I22, int the space I23 below the p l t valve pi ton I04.

When high pressure fluid flows into the space I23 below the pilot valve piston I04, it exerts an upward force on the pilot valve piston tendin to move it upwardly against the action of the pilot valve spring I05. Althou h the space I23 is in communication with the low pressure existing in the discharge pipe 32, as described above, such communication is restricted by the relatively small cross-sectional area of the helical groove I 25 and, conseouently, there is a substantial fluid pressure drop through the groove. The spring I05 is selected so that only a small fluid pressure drop through the helical groove I25 will be sufficient to buil up enou h fiuiri pressure beneath the pilot valve piston I04 to overbalance the spring and raise the piston. As soon as the fluid pressure in the space ,I23 v.risesto ,a value at which it oVerbaIanc'es the force exerted by the spring I05 and the weight of the: pilot valve piston assembly, thepilotvalvepistonI04 moves upwardly, carrying with it the pilot valve 5I, to open the latter. Ofcourse, fluid in the space I23 bleeds therefrom through the'helical groove I25 and the escape vent I28 so long as the master control valve 60 is open.

When the pilot valve 5I opens, power oil under high pressure can then flow directh from the inlet port 28, the axial passage52, the passage I I6, past the pilot valvef5l, through the annular space H! and the radial port H8 into thespace II9 below the main valve piston I08, to exert an upward force on the ,main valve piston tending to ,move it upwardly against tl1e;action of the main valve springs; III, and 2. Since thearea of the bottomof, the :main valve piston I08 is substantially greaterthan the: area of the main valve head I09, the fluid pressurein the space I I9 required to overloalancethe springs I II and I I2 is substantiallylower thanthe pressure required in the inlet port 28 to accomplish the same effect. Although the space II9 is in constant communication with the discharge pipe 32 through the helical groove I20, the cross-section area of the groove is small enough'to create a substantial fluid pressure droptherethrough and, thus, fluid pressure quickly builds up in the space I I9. When the fluid pressure in ,the space I9 overbalances the action of the main valvezsprings'l II and I I2, the main valve piston I08 rises, toopen the main valve 50. Power oil can then flow directly from the inlet port-20m the discharge pipe .I5a, through the main. flow passages 51, as described hereinabove, untilthefluidpressure in the inlet port and, consequentlythe upward fluid pressure on the valve head I8, is overbalanced by'the force exerted by the'spring 80, atwhich point the valve head lilseatson its seat TI to close the master control valve'x60. Upon such closure of the master control valve 60, the fluid pressures on the upper and lower faces of the pilot valve piston I04 quickly equalize; to permit the spring I05 to close the pilot valve 5|. 'As soon as the pilot valve 5| closes,*the fluid pressures on the upper and lower faces of the main valve piston I similarly equalize, permitting the main valve springs I I I and I [2 to close the main valve 50.

As will be apparent from the foregoing description, adjustment of the tension on the spring 80 of the master control valve 60 will permit the valve to be set to open at any desired predetermined maximum fluid pressure existing in the inlet port 28 below thevalue of the springs III and H2. This will'permit ready and close regulation of the maximum'fluid pressure in the manifold 20and in the supply manifold I2, to suit well pumping conditions. As pointed out above, the thimble'84 and skirt 86 may be calibrated directly in pounds per square inch, to indicate the maximum pressure to'which the master control valve 00 is set.

The pilot valve andits actuating piston I04 'ment by reducing the-force which causes'it' to 75 tances.

open. Theefiect of this influenceis transmitted along the chain of equilibrium to the control valve 00. Because the pilot valve 5| is never quite asfar open as it would be if it were not seated in the main valve head, the control valve is required to open a little more in order to produce the extent of opening of the pilot valve which will result in an equilibrating extent of opening of the main valve. To produce the additional opening of the control valve requires somewhat more pressure at the control valve head, and this results in extending the range of pressure through which the valves must hunt to find an equilibrating level. With even a slightly extended hunting range, chattering of any of the valves as they seek equilibrium is practically eliminated. The degree to which the dampening influence extends thehunting range may be controlled by suitable selection of the cross-area and length of the helical groove I20. By increasing the resistance of this groove, the effect of a small opening of the pilot valve5I upon the opening of the main valve 50 may be made greater, and the requisite opening'of the control valve, and therefore its hunting range, may be reduced.

When the main valve 50 acts as a safety valve independently of the functioning of the control valve 00, it pushes upon the needle I02 of the pilot valve 5|, keeping the pilot valve closed, and the main vale piston I00 has a dash-pot action, drawing fluid into the space I I 9 below the piston through the resistance of the helical groove I20. When the excess pressure has been relieved and the springs III and II2move the main valve 50 again towards closed position, the fluid just drawn into the space H9 is again forced through the helical groove I20, and sudden movement or chattering of the main valve is prevented. Fluid is, of course, also drawn in and forced out through the helical groove I25 to the space I23 below the pilot valve piston I04, assuming that the control valve 00 is closed, increasing the dash-pot effect on opening movement of the main valve and not decreasing it on the closing movement so long as the closing movement of the pilot valve keeps pace with that of the main valve.

As has been seen, the resistance afforded by the helical groove I20 affects the hunting range of the valves. This is also true of the resistance afforded by the helical groove I25 on the pilot valve stem I00, because the responsiveness of the pilot valve piston I 04 is directly affected by the pressure drop across the helical groove I25. The resistance of both of thehelical grooves I20 and I25 are variable automatically in a manner tending to increase the hunting range of the Valves as the volumeof fluid passing from the supply manifold I2 to the production pipe 0 increases. When the pistons respective to these two grooves are raised to open thevalves respective thereto, the upper portions of the helical grooves become uncovered and, of course, ineffective as resis- This facilitates the escape of pressure from the high pressurev sides of the respective piston, and therefore requires additional pressure to be supplied by the control valve 00 to achieve an equilibrating extent of opening of the main valve50. The equilibrating level of pressureis therefore raised slightly and the hunting range of the valves is increased. The extent of the increase in the hunting range varies with the extent of opening of the main valve requisite to maintain an equilibrating level of pressure, or, in other words, is automatically variable with respect to the volume of fluid whichmust be released in order not to exceed the desired pressure level.

As suggested hereinabove, the pressure of the power oil in the supply manifold I2 is normally maintained slightly above the maximum pressure required by either of the well pumps in the wells 9 and 9a. Consequently, during normal operation the 'by-pass valve l5 will remain slightly open to relieve this pressure and by-pass power oil from the supply manifold l2 back to the settling tank 1. If the well 9a is shut out of the system, by closing the metering valve Ma, the volume of power oil normally required to operate the well pump in well 9a will obviously be backed up into the supply system in the supply manifold l2, and this will tend to increase the fluid pressure in the supply manifold which, in turn, will cause the by-pass valve IE to open sufliciently to by-pass the increased unused volume of power oil to the settling tank 1 without appreciably varying the pressure of the power oil in the supply manifold. It will thus be appreciated that any or all of the well pumps in the system may be shut-off or reduced as to their power oil requirements, and all of the excess power oil remaining in the supply system is bypassed by the b-y-pass valve I5 to the settling tank. In addition, and more important, any such excess power oil is by-passed by the by-Dass valve IS without varying the fluid pressure in the supply manifold 52 more than 2%, regardless of the volume of power oil =by-passed, from zero to the full capacity 01 the supply system.

Changes in the strength of springs, the areas of pistons and unbalanced valves, and the resistance to flow afforded by the various passage will be readily apparent to one skilled in the art, and such changes do not depart from the spirit of my invention, nor do such alterations of arrangement as fall within the scope of the following claims.

I claim as my invention:

1. In a bypass valve connectible between a high pressure line and a low pressure line, the combination of: main passage means having an inlet connectible to the high pressure line and an outlet connectible to the low pressure line; pressureactuable main valve means including a main valve in said main passage means and including main piston means connected to said main valve for regulating flow through said main passage means from said inlet to said outlet, said main valve being movable toward its open position by pressure applied to one side of said main piston means; pilot passage means communicating with said main passage means between said inlet and said main valve and communicating with said one side of said main piston means; pressureactuable pilot valve means including a pilot valve in said pilot passage means and including pilot piston means connected to said pilot valve for regulating the pressure applied to said one side of said main piston means, said pilot valve being movable toward its open position by pressure applied to one side of said pilot piston means; control passage means communicating with said main passage means between said inlet and said main valve and communicating with said one side of said pilot piston means; and pressureactuable control valve means including a control valve in said control passage means for regulating the pressure applied to said one side of said pilot piston means, said control valve being movable toward its open position by a predetermined 12 maximum pressure in said main passage means between said inlet and said main valve.

2. In a bypass valve connectible between a high pressure line and a low pressure line, the combination of: main passage means having an inlet connectible to the high pressure line and an outlet connectible to the low pressure line; pressureactuable main valve means including a main valve in said main passage means and including main piston means connected to said main valve for regulating flow through said main passage means from said inlet to said outlet, said main valve being movabl toward its open position by pressure applied to one side of said main piston means; pilot passage means communicating with said main passage means between said inlet and said main valve and communicating with said one side of said main piston means; pressureactuable pilot valve means including a pilot valve in said pilot passage means and including pilot piston means connected to said pilot valve for regulating the pressure applied to said one side of said main piston means, said pilot valve being movable toward its open position by pressure applied to one side of said pilot piston means; and means spaced from said pilot valve means and communicating with said main passage means between said inlet and said main valve and communicating with one side of said pilot piston means and actuable by a predetermined maximum pressure in said main passage means between said inlet and said main valve for applying pressure to said one side of said pilot piston means.

3. A bypass valve according to claim 1 wherein said pilot passage means also communicates between said one side of said main piston means and said main passage means intermediate said main valve and said outlet, and wherein said control passage means also communicates between said one side of said pilot piston means and said main passage means intermediate said main valve and said outlet.

4. A bypass valve as defined in claim 3 wherein said pilot passage means is provided with a restricted portion between said one side of said main piston means and where it communicates with said main passage means intermediate said main valve and said outlet, and wherein said control passage means is provided with a restricted portion between said one side of said pilot piston means and'where it communicates with said main passage means intermediate said mean valve and said outlet.

5. A bypass valve according to claim 4 wherein the other side of said main piston mean and the other side of said pilot piston means communicate with said main passage means intermediate said main valve and said outlet.

6. A bypass valve according to claim 1 wherein said control valve means includes resilient means engaging said control valve and biasing it toward its closed position, and includes means engaging said resilient means for adjusting the biasing force applied to said control valve by said resilient means, whereby to vary the predetermined maximum pressure in said main passage means between said inlet and said main valve at which said control valve opens.

'7. A bypass valve according to claim 1 wherein said pilot passage means extends through said main valve mean and wherein said pilot valve is engageable with a seat in said main valve means, said main and pilot valves being mounted for movement toward their respective open positlons in the same direction so that openin movement of said main valve tends to close said pilot valve.

8. A bypass valve according to claim 1 wherein said control valve includes a nozzle and a plane member engageable with the end of said nozzle.

9. A bypass valve as defined in claim 1 wherein said main valve is provided with an area exposed to pressure in said main passage means between said main valve and said inlet, said main valve being mounted for movement toward its open position by a predetermined maximum pressure acting on said area.

10. In a bypass valve connectible between a high pressure line and a low pressure line, the combination of: main passage means having an inlet connectible to the high pressure line and an outlet connectible to the low pressure line; pressure-actuable main valve means including a main valve in said main passage means for regulating flow through said main passage means from said inlet to said outlet; control passage means communicating with said main passage means between said inlet and said main valve; pressure-actuable control valve means including a control valve in said control passage means, said control valve being movable toward its open position by a predetermined maximum pressure in said main passage means between said inlet maximum pressure in said main passage means between said inlet and said main valve, including a piston on said main valve and including pilot valve means controlled by said control valve means for applying pressure to said piston in a direction to open said main valve.

CLARENCE J. COBERLY.

References Cited in the file of this patent UNITED STATES PATENTS Number Name 7 Date 382,643 Fox May 8, 1888 591,013 Schreidt Oct. 5, 1897 1,014,435 Auld Jan. 9, 1912 1,229,726 Ebeling June 12, 1917 1,976,820 Wettstein Oct. 16, 1934 2,169,703 Mason Aug. 15, 1939 2,256,365 Wentworth Sept. 16, 1941 2,277,569 Vickers Mar. 24, 1942 2,375,410 Gondek et a1. May 8, 1945 2,520,893 Stevenson Aug. 29, 1950 

